1 /* SPDX-License-Identifier: GPL-2.0 */
3 * include/linux/random.h
5 * Include file for the random number generator.
7 #ifndef _LINUX_RANDOM_H
8 #define _LINUX_RANDOM_H
10 #include <linux/list.h>
11 #include <linux/once.h>
13 #include <uapi/linux/random.h>
15 struct random_ready_callback {
16 struct list_head list;
17 void (*func)(struct random_ready_callback *rdy);
21 extern void add_device_randomness(const void *, unsigned int);
22 extern void add_bootloader_randomness(const void *, unsigned int);
24 #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
25 static inline void add_latent_entropy(void)
27 add_device_randomness((const void *)&latent_entropy,
28 sizeof(latent_entropy));
31 static inline void add_latent_entropy(void) {}
34 extern void add_input_randomness(unsigned int type, unsigned int code,
35 unsigned int value) __latent_entropy;
36 extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
38 extern void get_random_bytes(void *buf, int nbytes);
39 extern int wait_for_random_bytes(void);
40 extern int __init rand_initialize(void);
41 extern bool rng_is_initialized(void);
42 extern int add_random_ready_callback(struct random_ready_callback *rdy);
43 extern void del_random_ready_callback(struct random_ready_callback *rdy);
44 extern int __must_check get_random_bytes_arch(void *buf, int nbytes);
47 extern const struct file_operations random_fops, urandom_fops;
50 u32 get_random_u32(void);
51 u64 get_random_u64(void);
52 static inline unsigned int get_random_int(void)
54 return get_random_u32();
56 static inline unsigned long get_random_long(void)
58 #if BITS_PER_LONG == 64
59 return get_random_u64();
61 return get_random_u32();
66 * On 64-bit architectures, protect against non-terminated C string overflows
67 * by zeroing out the first byte of the canary; this leaves 56 bits of entropy.
70 # ifdef __LITTLE_ENDIAN
71 # define CANARY_MASK 0xffffffffffffff00UL
72 # else /* big endian, 64 bits: */
73 # define CANARY_MASK 0x00ffffffffffffffUL
76 # define CANARY_MASK 0xffffffffUL
79 static inline unsigned long get_random_canary(void)
81 unsigned long val = get_random_long();
83 return val & CANARY_MASK;
86 /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes).
87 * Returns the result of the call to wait_for_random_bytes. */
88 static inline int get_random_bytes_wait(void *buf, int nbytes)
90 int ret = wait_for_random_bytes();
91 get_random_bytes(buf, nbytes);
95 #define declare_get_random_var_wait(var) \
96 static inline int get_random_ ## var ## _wait(var *out) { \
97 int ret = wait_for_random_bytes(); \
100 *out = get_random_ ## var(); \
103 declare_get_random_var_wait(u32)
104 declare_get_random_var_wait(u64)
105 declare_get_random_var_wait(int)
106 declare_get_random_var_wait(long)
107 #undef declare_get_random_var
109 unsigned long randomize_page(unsigned long start, unsigned long range);
111 u32 prandom_u32(void);
112 void prandom_bytes(void *buf, size_t nbytes);
113 void prandom_seed(u32 seed);
114 void prandom_reseed_late(void);
117 __u32 s1, s2, s3, s4;
120 u32 prandom_u32_state(struct rnd_state *state);
121 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
122 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
124 #define prandom_init_once(pcpu_state) \
125 DO_ONCE(prandom_seed_full_state, (pcpu_state))
128 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
129 * @ep_ro: right open interval endpoint
131 * Returns a pseudo-random number that is in interval [0, ep_ro). Note
132 * that the result depends on PRNG being well distributed in [0, ~0U]
133 * u32 space. Here we use maximally equidistributed combined Tausworthe
134 * generator, that is, prandom_u32(). This is useful when requesting a
135 * random index of an array containing ep_ro elements, for example.
137 * Returns: pseudo-random number in interval [0, ep_ro)
139 static inline u32 prandom_u32_max(u32 ep_ro)
141 return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
145 * Handle minimum values for seeds
147 static inline u32 __seed(u32 x, u32 m)
149 return (x < m) ? x + m : x;
153 * prandom_seed_state - set seed for prandom_u32_state().
154 * @state: pointer to state structure to receive the seed.
155 * @seed: arbitrary 64-bit value to use as a seed.
157 static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
159 u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
161 state->s1 = __seed(i, 2U);
162 state->s2 = __seed(i, 8U);
163 state->s3 = __seed(i, 16U);
164 state->s4 = __seed(i, 128U);
167 #ifdef CONFIG_ARCH_RANDOM
168 # include <asm/archrandom.h>
170 static inline bool __must_check arch_get_random_long(unsigned long *v)
174 static inline bool __must_check arch_get_random_int(unsigned int *v)
178 static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
182 static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
188 /* Pseudo random number generator from numerical recipes. */
189 static inline u32 next_pseudo_random32(u32 seed)
191 return seed * 1664525 + 1013904223;
194 #endif /* _LINUX_RANDOM_H */